1. Field
Example embodiments relate to a photodiode including an organic semiconductor.
2. Description of the Related Art
The resolution of an image sensor including a photodiode becomes higher, and thus, the size of a pixel becomes decreased. The reduction of the pixel size may cause the decrease of the absorption area that in turn reduces the sensitivity of a silicon photodiode.
Therefore, organic semiconductors having a higher extinction coefficient and higher wavelength selectivity compared with silicon are being considered as photoelectric materials of a photodiode.
A photodiode including an organic semiconductor as a photoelectric material generally has a triple-layered structure that includes a P-type semiconductor, an intrinsic layer, and an N-type semiconductor. The intrinsic layer is formed by co-depositing a P-type semiconductor and an N-type semiconductor. The intrinsic layer absorbs light to produce excitons, and the excitons are divided into holes and electrons at a joint surface of the N-type semiconductor and the P-type semiconductor. The holes and electrons move to electrodes to generate current. However, the external quantum efficiency and the light responsivity of the above-described photodiode may not be desirable.